This study was painted at dawn so it was still dark outside. It is painted on carton board which is an interesting surface. It is the color of cardboard and quite "scratchy" in texture. Carton board is also very absorbent so the color change is more noticeable when dry versus linen. The impressionsts used a similar surface for their oil sketches at the turn of the last century. I like it for studies and sketches but the drawback is that it has to be framed under glass (as do all works on paper) .